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Biomedical subjects

S Serafini

Publications and source records attributed to S Serafini.

At least 19 recordsLinked to original sources
PubMed2006

Administration of fludarabine-loaded autologous red blood cells in simian immunodeficiency virus-infected sooty mangabeys depletes pSTAT-1-expressing macrophages and delays the rebound of viremia after suspension of antiretroviral therapy.

A major limitation of highly active antiretroviral therapy is that it fails to eradicate human immunodeficiency virus (HIV) infection due to its limited effects on viral reservoirs carrying replication-competent HIV, including monocytes/macrophages (M/M). Therefore, therapeutic approaches aimed at targeting HIV-infected M/M may prove useful in the clinical management of HIV-infected patients. In previous studies, we have shown that administration of fludarabine-loaded red blood cells (RBC) in vitro selectively induces cell death in HIV-infected M/M via a pSTAT1-dependent pathway. To determine the in vivo efficacy of this novel therapeutic strategy, we treated six naturally simian immunodeficiency virus (SIV)-infected sooty mangabeys (SMs) with either 9-[2-(R)-(phosphonomethoxy)propyl]adenine (PMPA) only, fludarabine-loaded RBC only, or PMPA in association with fludarabine-loaded RBC. The rationale of this treatment was to target infected M/M with fludarabine-loaded RBC at a time when PMPA is suppressing viral replication taking place in activated CD4+ T cells. In vivo administration of fludarabine-loaded RBC was well tolerated and did not induce any discernible side effect. Importantly, addition of fludarabine-loaded RBC to PMPA delayed the rebound of viral replication after suspension of therapy, thus suggesting a reduction in the size of SIV reservoirs. While administrations of fludarabine-loaded RBC did not induce any change in the CD4+ or CD8+ T-cell compartments, we observed, in chronically SIV-infected SMs, a selective depletion of M/M expressing pSTAT1. This study suggests that therapeutic strategies based on the administration of fludarabine-loaded RBC may be further explored as interventions aimed at reducing the size of the M/M reservoirs during chronic HIV infection.

Adenine↗
PubMed2004

Effect of listeriolysin O-loaded erythrocytes on Mycobacterium avium replication within macrophages.

OBJECTIVE: To evaluate the efficacy of erythrocytes loaded with the haemolytic toxin listeriolysin O against Mycobacterium avium replication within human macrophages. METHODS: Recombinant listeriolysin O was loaded in human erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to allow them to be recognized and taken up by human macrophages infected with M. avium. The antimycobacterial activity of the erythrocytes loaded with listeriolysin O was evaluated by supernatant and intracellular cfu counts on days 4 and 7 post-erythrocyte administration. RESULTS: Recombinant listeriolysin O was encapsulated in human erythrocytes to reach final concentrations ranging from 1 to 4 ng/mL of erythrocytes. Erythrocytes loaded with increasing quantities of recombinant protein were able to reduce (at most by 50%) M. avium replication in a dose-dependent fashion when administered to infected macrophages. CONCLUSIONS: Erythrocytes loaded with listeriolysin O are effective against M. avium replication within macrophages. We are confident that the strategy presented could be useful against mycobacteria other than M. avium (such as Mycobacterium tuberculosis and Mycobacterium leprae) by itself or as part of an antimycobacterial treatment.

Bacterial Toxins↗
PubMed2004

Advanced diagnostic tools: virtual colonoscopy and magnifying chromoendoscopy.

Early endoscopic diagnosis of colorectal cancers (CRCs) represents the best tool for the reduction of CRC mortality, but the conventional colonoscopic view seems unable to clarify faint changes of colorectal mucosa. For these reasons, during the last few decades, two new techniques have been developed in order to better define, diagnose and treat colorectal lesions: chromoendoscopy (CE) and magnifying chromoendoscopy (MC). The authors herein highlight the benefits of both and compare the results of conventional endoscopy and CE with 0.2% indigo carmine solution, evaluating 995 consecutive selected patients referred for colonoscopy between January 1999 and March 2003 at the International Health Union of Rome. CE showed new neoplastic patterns not detectable with conventional endoscopy in 102 patients (10.2%). The incidence of high-grade dysplasia and early carcinomas was 9.9% for protruded, 13.1% for flat and 60% for depressed lesions. Our comparative study on 995 consecutive selected patients confirmed the existence of flat and depressed neoplasms in Italy and shows the high accuracy rate of CE over conventional endoscopy for the detection of non-polypoid lesions. CE should be used routinely in order to enhance the early diagnosis of CRCs, while MC in experienced hands represents a significant advance in colonoscopic practice improving the diagnosis of every single lesion, enhancing therapeutic efficacy of colorectal tumours.

Colonography, Computed Tomographic↗
PubMed2003

Fine distribution of CLOCK protein in hepatocytes of hibernating dormice.

CLOCK protein is a member of the bHLH-PAS family of transcription factors, it is expressed in several tissues including the liver and is essential for normal circadian rhythms. In this study we investigate the distribution of CLOCK protein in hepatocytes of euthermic and hibernating edible dormice Glis glis as well as in hepatocytes taken from the hibernating animals submitted in vitro to experimental conditions mimicking the arousal process. Our results demonstrate that CLOCK protein is expressed in all animals and is mostly located in the nucleus, in particular, on perichromatin fibrils and nucleoli. During deep hibernation CLOCK protein becomes more abundant but an intracellular redistribution occurs: the protein significantly decreases in all cellular compartments, but it accumulates in the amorphous bodies. These nuclear bodies, typical of the hibernating state, probably represent storage sites for CLOCK protein to be quickly used upon arousal. Accordingly, in hepatocytes submitted to in vitro conditions mimicking arousal CLOCK protein levels rapidly reach the euthermic values, while amorphous bodies disappear.

Animals↗
PubMed2001

fMRI auditory language differences between dyslexic and able reading children.

During fMRI, dyslexic and control boys completed auditory language tasks (judging whether pairs of real and/or pseudo words rhymed or were real words) in 30 s 'on' conditions alternating with a 30 s 'off' condition (judging whether tone pairs were same). During phonological judgment, dyslexics had more activity than controls in right than left inferior temporal gyrus and in left precentral gyrus. During lexical judgment, dyslexics were less active than controls in bilateral middle frontal gyrus and more active than controls in left orbital frontal cortex. Individual dyslexics were reliably less active than controls in left insula and left inferior temporal gyrus. Dyslexic and control children differ in brain activation during auditory language processing skills that do not require reading.

Acoustic Stimulation↗
PubMed2001

Comparison of fMRI and PEPSI during language processing in children.

The present study explored the correlation between lactate as detected by MR spectroscopy (MRS) and blood oxygenation level dependent (BOLD) responses in male children during auditory-based language tasks. All subjects (N = 8) participated in one proton echo planar spectroscopic imaging (PEPSI) and one functional magnetic resonance imaging (fMRI) session that required phonological and lexical judgments to aurally presented stimuli. Valid PEPSI data was limited in the frontal areas of the brain due to the magnetic susceptibility of the eye orbits and frontal sinuses. Findings from the remainder of the brain indicate that subjects show a significant consistency across imaging techniques in the left temporal area during the lexical task, but not in any other measurable area or during the phonological task. Magn Reson Med 45:217-225, 2001.

Adolescent↗
PubMed2001

Low-molecular-weight heparin versus warfarin for secondary prophylaxis of venous thromboembolism: a cost-effectiveness analysis.

PURPOSE: To compare the cost effectiveness of low-molecular-weight heparin with that of oral anticoagulants in preventing recurrences after an episode of venous thromboembolism. METHODS: A decision tree was used to assess the cost and the expected quality-adjusted years of life (QALY) after treatment with either low-molecular-weight heparin or warfarin, based on pooled data from six published trials. Preferences were elicited with a modified time trade-off method in a sample of patients attending an anticoagulation clinic. RESULTS: Compared with warfarin, low-molecular-weight heparin significantly decreased the rate of minor bleeding (odds ratio [OR] = 0.24; 95% confidence interval [CI]: 0.14 to 0.43) but not recurrent deep vein thromboses (OR = 0.77; 95% CI: 0.43 to 1.35). Patients' preference for warfarin (0.988, on a 0 to 1 scale) was lower than that for low-molecular-weight heparin (0.992), but the difference was not statistically significant. A Monte Carlo analysis estimated that low-molecular-weight heparin saved an average of 13 quality-adjusted days compared with warfarin, at a cost of $6,583 per QALY (95% CI: $5,525 to $7,625) based on costs in Italy and $28,231 per QALY (95% CI: $20,872 to $36,773) based on costs in the United States. When we included rebound recurrences after interruption of therapy, which were more common with low-molecular-weight heparin, treatment with low-molecular-weight heparin cost $53,166 per QALY in Italy and $177,166 per QALY in the United States. CONCLUSIONS: Low-molecular-weight heparin might be a cost-effective drug for secondary prophylaxis of venous thromboembolism, especially in patients at high risk of recurrence and where the drug's cost is lower. The apparent increase in recurrence after interruption of therapy needs to be investigated more thoroughly before low-molecular-weight heparin can be recommended routinely.

Administration, Oral↗
PubMed2001

Erythrocyte-mediated delivery of dexamethasone in patients with chronic obstructive pulmonary disease.

Human erythrocytes from ten patients with chronic obstructive pulmonary disease (COPD) were loaded with increasing amounts of dexamethasone 21-phosphate and were re-infused into the original donors. Drug-loaded erythrocytes acted as circulating bioreactors, converting the non-diffusible dexamethasone 21-phosphate into the diffusible dexamethasone. Pharmacokinetic analyses on these patients showed that a single administration of drug-loaded erythrocytes was able to maintain detectable dexamethasone concentrations in blood for up to seven days. This continuous release of dexamethasone was paralleled by the suspension of beta2-agonist and oral corticosteroid treatments by all of the patients. Thus dexamethasone 21-phosphate-loaded erythrocytes are safe carriers for corticosteroid analogues and are a useful alternative to frequent oral or inhaled drugs in elderly patients with COPD.

Aged↗
PubMed2001

Erythrocyte-mediated delivery of a new homodinucleotide active against human immunodeficiency virus and herpes simplex virus.

Monocyte-derived macrophages (MDMs) play a central role in the pathogenesis of infection by human immunodeficiency virus (HIV-1) and represent one of the main reservoirs of the virus in the body. In addition, MDMs can easily be infected by various herpes viruses, including herpes simplex virus type 1 (HSV-1). We have synthesized a new antiviral agent (Bis-PMEA) that consists of two 9-(2-phosphonylmethoxyethyl)adenine (PMEA) molecules bound by a phosphate bridge. This nucleotide analogue, like the parent compound PMEA, has strong and selective activity against HIV-1 and HSV-1. A drug-targeting system previously developed in our laboratory was used for the selective delivery of these drugs to macrophages. Bis-PMEA and PMEA were encapsulated into autologous erythrocytes by a procedure of hypotonic dialysis and isotonic resealing. Loaded erythrocytes were modified to increase their recognition and phagocytosis by human macrophages. By administering Bis-PMEA-loaded erythrocytes to macrophages, 47% of Bis-PMEA and 28% of PMEA was still present 10 days after phagocytosis; in contrast, only 12% of PMEA was found in macrophages receiving PMEA-loaded erythrocytes. Bis-PMEA-loaded erythrocytes were then added to macrophages infected with HIV-1 and HSV-1 and their antiviral activity evaluated. Remarkable protection was obtained against HIV-1 and HSV-1 infection (95 and 85%, respectively). Therefore, Bis-PMEA acts as an efficient antiviral prodrug that, following selective targeting to macrophages by means of loaded erythrocytes, can protect a refractory cell compartment.

Adenine↗
PubMed2001

Inhibition of HIV-1 replication in macrophages by red blood cell-mediated delivery of a heterodinucleotide of azidothymidine and 9-(R)-2-(phosphono methoxypropyl)adenine.

Monocyte-derived macrophages (M/M) are considered important in vivo reservoirs for different kinds of viruses, including HIV. Hence, therapeutic strategies are urgently needed to protect these cells from virus infection or to control viral replication. In this paper, we report the synthesis, target delivery and in vitro efficacy of a new heterodinucleotide (AZTpPMPA), able to inhibit HIV-1 production in human macrophages. AZTpPMPA consists of two established anti-HIV drugs [zidovudine (AZT) and tenofovir (PMPA)] chemically coupled together by a phosphate bridge. This drug is not able to prevent p24 production when administered for 18 h to M/M experimentally infected with HIV-1 Bal (inhibition 27%), but can almost completely suppress virus production when given encapsulated into autologous erythrocytes (inhibition of p24 production 97%). AZTpPMPA is slowly converted to PMPA, AZT monophosphate and AZT (36 h half-life at 37 degrees C) by cell-resident enzymes. Thus AZTpPMPA should be considered a new prodrug of AZT and PMPA that is able to provide stechiometric amounts of both nucleoside analogues to macrophage cells and to overcome the low phosphorylating activity of M/M for AZT and the modest permeability of PMPA.

Adenine↗
PubMed2000

Biochemical characterization of a hepatitis C virus RNA-dependent RNA polymerase mutant lacking the C-terminal hydrophobic sequence.

The RNA-dependent RNA polymerase activity of hepatitis C virus is carried out by the NS5B protein. The full-length protein was previously purified as a non-fusion protein from insect cells infected with a recombinant baculovirus. The characterization is now described of a C-terminal hydrophobic domain deletion mutant of NS5B purified from E. coli. In addition to increased solubility, deletion of this sequence also positively affected the polymerase enzymatic activity. The efficiency of nucleotide polymerization of both the full-length and the C-terminal truncated enzymes were compared on homopolymeric template-primer couples as well as on RNA templates with heteropolymeric sequences. The largest difference in the polymerase activity was observed on the latter. On all the templates, the increased activity could be ascribed, at least in part, to enhanced template turnover of the deletion mutant with respect to the full-length enzyme. The elongation rates of the two enzyme forms were compared under single processive cycle conditions. Under these conditions, both the full-length and the deletion mutant were able to incorporate about 700 nt/min.

Animals↗
PubMed2000

Effects of a phonologically driven treatment for dyslexia on lactate levels measured by proton MR spectroscopic imaging.

BACKGROUND AND PURPOSE: Dyslexia is a language disorder in which reading ability is compromised because of poor phonologic skills. The purpose of this study was to measure the effect of a phonologically driven treatment for dyslexia on brain lactate response to language stimulation as measured by proton MR spectroscopic imaging. METHODS: Brain lactate metabolism was measured at two different time points (1 year apart) during four different cognitive tasks (three language tasks and one nonlanguage task) in dyslexic participants (n = 8) and in control participants (n = 7) by using a fast MR spectroscopic imaging technique called proton echo-planar spectroscopic imaging (1 cm3 voxel resolution). The age range for both dyslexic and control participants was 10 to 13 years. Between the first and second imaging sessions, the dyslexic boys participated in an instructional intervention, which was a reading/science workshop. RESULTS: Before treatment, the dyslexic boys showed significantly greater lactate elevation compared with a control group in the left anterior quadrant (analysis of variance, P = .05) of the brain during a phonologic task. After treatment, however, brain lactate elevation was not significantly different from that of the control group in the left anterior quadrant during the same phonologic task. Behaviorally, the dyslexic participants improved in the phonologic aspects of reading. CONCLUSION: Instructional intervention that improved phonologic performance in dyslexic boys was associated with changes in brain lactate levels as measured by proton echo-planar spectroscopic imaging.

Brain↗
PubMed1999

Metabolism, mitochondrial uptake and toxicity of 2', 3'-dideoxycytidine.

2',3'-Dideoxycytidine (ddCyd) is a prescription anti-retroviral drug that causes mitochondrial toxicity and peripheral neuropathy. ddCyd is actively phosphorylated by cytosolic deoxycytidine kinase and nucleoside (di)phosphate kinase to the 5'-triphosphate derivative. However, 2',3'-dideoxycytidine 5'-diphosphocholine (ddCDP-choline) was also found in human cells incubated with ddCyd. In this paper we show that ddCDP-choline is produced from dideoxyCTP (ddCTP) and phosphocholine by phosphocholine cytidylyltransferase. dCTP and CTP appear to activate this synthesis in a concentration-dependent manner. Although ddCTP and ddCDP-choline can both enter the mitochondria, ddCDP-choline uptake is more efficient than ddCTP uptake. These data suggest that ddCDP- choline is the ddCyd metabolite that is probably responsible for mitochondrial toxicity. The uptake of ddCTP and ddCDP-choline by mitochondria is inhibited by 3.0 mM l-carnitine in the cell-free system investigated; when added to U937 cells grown in the presence of 0.25 microM ddCyd, 3.0 mM l-carnitine partially abrogated the mitochondrial toxicity of ddCyd.

Animals↗
PubMed1999

A high-throughput radiometric assay for hepatitis C virus NS3 protease.

A novel radiometric in vitro assay for discovery of inhibitors of hepatitis C viral protease activity, suitable for high-throughput screening, was developed. The NS3 protein of hepatitis C virus (HCV) contains a serine protease, whose function is to process the majority of the nonstructural proteins of the viral polyprotein. The viral NS4A protein is a cofactor of NS3 protease activity in the cleavage of NS3-NS4A, NS4A-NS4B, NS4B-NS5A, and NS5A-NS5B junctions. To establish an in vitro assay system we used NS3 proteases from different HCV strains, purified from Escherichia coli and a synthetic radiolabeled peptide substrate that mimics the NS4A-NS4B junction. Upon incubation with the enzyme the substrate was separated from the radiolabeled cleavage product by addition of an ion exchange resin. The assay was performed in a microtiter plate format and offered the potential for assaying numerous samples using a laboratory robot. Taking advantage of these features, we used the assay to optimize reaction conditions by simultaneously varying different buffer components. We showed that physicochemical conditions affect NS3 protease activity in a strain-specific way. Furthermore, the sensitivity of the assay makes it suitable for detection and detailed mechanistic characterization of inhibitors with low-nanomolar affinities for the HCV serine protease.

Buffers↗
PubMed1999

Dyslexic children have abnormal brain lactate response to reading-related language tasks.

BACKGROUND AND PURPOSE: Children with dyslexia have difficulty learning to recognize written words owing to subtle deficits in oral language related to processing sounds and accessing words automatically. The purpose of this study was to compare regional changes in brain lactate between dyslexic children and control subjects during oral language activation. METHODS: Brain lactate metabolism was measured during four different cognitive tasks (three language tasks and one nonlanguage task) in six dyslexic boys and in seven control subjects (age- and IQ-matched right-handed boys who are good readers) using a fast MR spectroscopic imaging technique called proton echo-planar spectroscopic imaging (1-cm3 voxel resolution). The area under the N-acetylaspartate (NAA) and lactate peaks was measured to calculate the lactate/NAA ratio in each voxel. RESULTS: Dyslexic boys showed a greater area of brain lactate elevation (2.33+/-SE 0.843 voxels) as compared with the control group (0.57+/-SE 0.30 voxels) during a phonological task in the left anterior quadrant. No significant differences were observed in the nonlanguage tasks. CONCLUSION: Dyslexic and control children differ in brain lactate metabolism when performing language tasks, but do not differ in nonlanguage auditory tasks.

Aspartic Acid↗
PubMed1997

Functional MR spectroscopy of the auditory cortex in healthy subjects and patients with sudden hearing loss.

PURPOSE: To use MR spectroscopy to study the biochemical changes produced by auditory stimuli in patients with sudden sensorineural hearing loss and to compare these findings with the biochemical changes seen in healthy volunteers. METHODS: Single-voxel MR spectroscopy was used to study biochemical changes in the auditory cortex in 11 control subjects and 19 patients with sudden sensorineural hearing loss. MR spectroscopic signals were measured during three different sound conditions (scanner noise, music, and sirens). RESULTS: A lower MR spectroscopic lactate signal was observed in control subjects during the music stimulus than during the other sound conditions. This music-induced lactate change was not observed in patients with hearing loss. The other proton metabolites (choline, creatine, N-acetylaspartate [NAA]) remained stable during the different auditory stimuli. However, the NAA/creatine ratio was higher in the auditory cortex of patients than in the control subjects, and was not dependent on the sound condition. CONCLUSION: The detection of stimulus-induced and stable biochemical MR spectroscopic changes in patients with hearing loss may be useful in assessing disease activity.

Acoustic Stimulation↗